Determination of 14 Trace Elements in Geochemical Samples by ICP-MS Using Kinetic Energy Discrimination Mode

Abstract

BACKGROUND Traditional inductively coupled plasma-mass spectrometry (ICP-MS) determination of trace elements such as Ag and Cd in geochemical samples is seriously affected by the matrix effect and multiple polyatomic ions, making it difficult to measure these elements accurately. OBJECTIVES To compare the results of ICP-MS standard mode (STD) and kinetic energy discrimination mode (KED), and determine the valid determination modes of each element. METHODS The samples were digested by HNO3-HF-HClO4, and the residue was dissolved in aqua regia. Under the KED mode, the isotopes with less interference were selected as the determination isotopes. Rh was used as the internal standard element to correct the signal drift, and the sample solution was diluted by 1000. Under these conditions, the matrix effect was minimized. RESULTS The productivity of matrix elements such as Zr and Nb oxides was reduced, and the interference of oxides on Ag and Cd was minimized under the KED mode. The KED mode improved the signal-to-noise ratio and reduced the detection limits of this method with Ag and Cd, detection limits of 0.004mg/kg and 0.005mg/kg, respectively. The detection limits of the other 12 elements were also lower than those of 76 element analysis schemes in a multi-objective geochemical survey. The accuracy of determination of trace elements was significantly better than that of the STD mode. CONCLUSIONS The method has been verified by the first-class national reference material and the analytical results are in good agreement with the certified values. The method provides high-quality data for exploration geochemistry.

Keywords

• rock
• soil
• sediment
• ag
• cd
• acid dissolution
• inductively coupled plasma-mass spectrometry
• kinetic energy discrimination